Microservices Questions to Nail Your Interview

Microservices are among the most vital components of many modern applications. The vast majority (75%) of firms with over 1,000 employees use microservices. Therefore, as a software developer, the chances that you interview for a firm that asks microservices interview questions are pretty high.

Companies like Paypal and Square have been using microservices for a long time. If you want to nail every one of your microservices interview questions, you’ll need to anticipate questions on every aspect, including:

• General microservices architecture interview questions
• Java microservices interview questions
• Microservices design patterns interview questions

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Why Companies Are Increasingly Using Microservices

Instead of taking a monolithic approach to designing system architecture, microservices seek to speed things up. Thus, they eliminate a lot of interdependence that comes with the traditional way of structuring software applications. By using microservice architecture, Chris Richardson claims that app delivery can become more rapid and frequent. As apps become more complex, microservices are increasingly relevant.

The great part about microservices is that they are each independently deployable. Meaning that if you want to test a certain microservice, you don’t need to take down the entire system for maintenance. It’s far more efficient.

General Microservice Architect Interview Questions

You can expect to hear these microservices questions in just about any programming interview.

Q1: Please Explain Microservices Architecture

A: Microservices architecture is a philosophy, a way of structuring the apps in your organization. To avoid having bugs in one part cause problems for your entire application, constructing the app from microservices isolates any errors and makes it quicker to find them and fix them. This makes different parts of the application more independent.

Every microservice will be responsible for a single function that your app needs. As businesses increasingly rely on these applications, it’s advisable to use microservices. Most companies are moving toward this architecture if they haven’t already.

Q2: Name the common tools used to deploy microservices architecture.

A: I can think of about 10 tools that one might use to build and manage microservice architecture:

• Mongo DB
• Kubernetes
• KAFKA
• Elasticsearch
• Jenkins
• Jaeger
• Fluent
• Docker
• Prometheus
• Grafan

Note that you don’t need to go into detail about each of these tools, here are three examples you can use.

MongoDB:

MongoDB is a NoSQL database which makes you far less constrained by the decisions you take at the outset of your database’s creation. In other words, it’s more flexible than SQL databases. It is also very fast and particularly appropriate for handling very large quantities of data. On the other hand MongoDB struggles to join tables, leading to data duplication problems.

Kubernetes:

Containers are ready-to-run software packages that contain everything the software needs in order to run. Kubernetes is like an operating system in the cloud that coordinates all of these containers, determining when they run and how many resources they get in order to keep everything running smoothly.

Kafka:

Kafka gets you to model your code as a stream of events stored in order in logs rather than as objects modeled by databases. Microservices are a natural pair with this way of thinking about code, with each service pulling data out of the Kafka logs or putting data in.

Q3: What Is The Difference Between Monolithic Architecture, Microservices Architecture, and Service-oriented Architecture? (SOA)

A: Let’s recognize that each of these styles is used to reach the same goal - to serve the application.

Monolithic architecture takes a holistic approach to program architecture. The entire application will exist as one piece, with various interdependent nodes. There are downstream consequences, however. If one aspect of the app's functionality breaks, the entire application can belly up. This even makes activities like regular maintenance a challenge.

By contrast, microservices architecture creates apps from several services that combine in a modular way. You can scale each of these services as needed and take them out easily if you find that they no longer serve your purposes.

Service-oriented architecture (SOA) means that services across programs and apps can communicate with each other. While you might employ microservices to help service a single app, service-oriented architecture has a wider scope. You would be thinking about SOA in the context of an entire enterprise.

Top Java Microservices Interview Questions

You’ll find that most of the Java microservices interview questions involve Spring Boot, which is of course a Java-based platform.

Q4: Discuss Spring Boot and its Relation to Microservices

Spring Boot is a platform that allows you to create stand-alone applications in the Spring Framework. These Spring applications are useful because they are designed to allow you to start with small applications and scale them easily. This makes it perfect for developers creating microservices.

One use case for microservices involves streaming data. You could use a Spring Cloud Stream to connect all your microservices with your real-time data. If you have an event-driven application, then this type of connection is vital.

Q5: What Are Some of the Problems That Spring Cloud Solves?

There are many issues that Spring Cloud solves, everything from latency and bandwidth issues and redundancy issues from distributed systems.

Network Issues

Large applications can encounter a whole host of network problems. Things like latency overhead and bandwidth issues can affect general performance which reduces everyone’s speed. Not to mention, there are also security considerations.

Load Balancing

When you use a distributed system, a lot of redundancy occurs and you waste a lot of resources. You need to distribute between network links, CPU, and so on. By its very nature, Spring Cloud eliminates many of these issues by allowing you to manage databases in the cloud.

Microservices Design Patterns Interview Questions

Companies want to know that you understand the various microservices design patterns that you could encounter.

Q6: What Are Design Patterns for Microservices?

We can discuss seven general types of design patterns for microservices. They are:

• Decomposition Patterns: deciding what logic to use to break the application up into functions, e.g. business areas.
• Integration Patterns: how to get different microservices to collaborate to deliver the desired goal.
• Database Patterns: how to design databases for microservices (one per microservice or shared?)
• Communication Patterns: choosing the most appropriate type of communication for communication between microservices (e.g. synchronous, asynchronous, event driven).
• Cross-cutting Concern Patterns: calling on different services while avoiding the need to reconfigure them.
• Observability Patterns: keeping track of requests that span multiple services
• Deployment Patterns: how you will deploy service instances (one per host? Multiple per host? One per container?)

Q7: What is the Reactive Extension in Microservices?

The Rx Java design pattern allows you to collect results by calling multiple microservices at once. Then, the reactive extension takes all these responses and compiles them into one response.

This makes it easy for you to write pure, immutable functions. For instance, Rx Java observables allow you to subscribe to events that occur all at once. This is important because many of today’s applications must account for simultaneous events as many users could be interacting with the app at once.

Q8: Name Some of the Advantages of Java Design Patterns

Design patterns exist for a reason. As a developer, you don’t want to program the same things over and over. It’s easy to reuse these patterns over multiple projects. Furthermore, you could create an entire template that allows you to outline system architecture. This will save you loads of time down the road.

These design patterns have been tested quite a bit over the last few years which makes large enterprises confident in adopting them. Therefore, you can count on Java design patterns to provide robust solutions. Not to mention, their simplicity makes communication between developers and handling documentation a lot easier.

Bonus: Use the STAR Method to Answer Microservices Interview Questions

While microservices questions tend to be technical, you would do well to impress the interviewer by telling them about a situation where you applied some of your programming skills to solve a tough situation. That’s where the STAR method comes in. STAR stands for:

• Situation
• Task
• Action
• Result

Let’s examine how you can use the STAR method to make yourself look like a star in a challenging setting.

Situation

First, you must come up with a work-related experience that fits the question that the interviewer is asking. Hopefully, you think of a recent situation to validate your core competencies. Don’t spend long on this part.

An example could be a time when you had to work on a tight deadline to finish a service essential to your current project.

Task

While the situation is very general, the task means the problem that had to be solved with an action. This is one where you could have a direct impact on the situation you previously outlined.

As a software developer, you could have had the task of creating a service that captured user events and sent them to your analytics platform.

Action

Now, you need to discuss the specific actions you took to solve the problem. Use the word “I” instead of “We” to put your achievements at the forefront. Discuss your achievements in resolving this situation at length.

For instance, you might have found a new shortcut when creating a microservice to deliver the analytics platform far more efficiently than before.

Result

Don’t be shy. You should broadcast your results with confidence. This should also be a success story in some way. Try to quantify your success if possible. The analytics platform might have started to load at speeds that were 40% faster. That could have positive downstream effects on the efficiency of your whole organization.

Sometimes, you can’t point to a quantitative result. In that case, try to wrap it up nicely by extracting an important lesson from the situation.

The Bottom Line

Since most enterprises today use microservices, you can count on getting a few microservices interview questions on your next programming interview. If you have worked with microservices in the past, then answering many of these questions will be a breeze. That said, you should still practice how to talk about microservices succinctly ahead of the interview regardless of your experience level.

If you’re working on landing your dream job, then why not make it one with a four-day work week?